critical mass

American  

[krit-i-kuhl mas] / ˈkrɪt ɪ kəl ˈmæs /

noun

1. Physics. the amount of a given fissionable material necessary to sustain a chain reaction at a constant rate.

   The critical mass for a bomb based on uranium fission is different than that for plutonium fission.

2. an amount necessary or sufficient to have a significant effect or to achieve a result.

   a critical mass of popular support.

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critical mass British  

noun

1. the minimum mass of fissionable material that can sustain a nuclear chain reaction

2. the minimum amount of money or number of people required to start or sustain an operation, business, process, etc

   the critical mass for a subscription digital sports channel

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Etymology

Origin of critical mass

First recorded in 1940–45

Example Sentences

The situation came to a critical mass in 2024 when Musk sued OpenAI for diverging from its nonprofit mission.

From Slate • Apr. 30, 2026

Participants at the Santa Marta meeting believe the real purpose of the meeting is to show those who are hesitating about the transition that there is a critical mass moving in favour of renewables.

From BBC • Apr. 24, 2026

With such fragmentation, it’s much harder for a negative storyline to reach critical mass.

From Los Angeles Times • Nov. 30, 2025

“What is less obvious is whether that will create the critical mass necessary to overcome the obstacles standing in the way of sports betting in the states that have yet to authorize it.”

From Barron's • Nov. 12, 2025

Each of these phases is specialized and unique, and neither India nor China nor Russia has a critical mass of talent that can handle the whole product cycle for a big American multinational.

From "The World Is Flat" by Thomas L. Friedman